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Discussion Starter · #1 · (Edited)
Anyone have experience with this particular HKS 2SX 45th Anniversary 2-stage valved exhaust?

Looks like piping is ~4" with electronic valves. Sounds like stock with valve closed and not annoying with it open. Only downside is no midpipe included.

Distributor networks are listing this is as clearance item at roughly 46% off which sounds enticing.

"Redesigning the original component to replace from the secondary catalyzer enables to eliminate unnecessary pipe diameter reduction and to withstand a higher engine power performance machine. (Available only for overseas markets since it does not comply with Japanese regulations.)

The diameter of the upper pipe is enlarged to 101.6mm from 85mm to withstand more than 1000ps.
The sound pressure is reduced approximately by 7dB※ when the valve is closed. This is the exhaust system that can be silent and withstand higher engine power.

The controller is a purpose-built. The engine RPM signal and speed signal are required to connect to the controller. The valve opens and closes automatically according to the engine RPM and speed. This exhaust system with the switchable valve can implement silence and high power together."

GT-R (R35):2 STAGE EXHAUST


Added comparison videos (9-19-2020)



Added 2-26-2021

With AMS catless downpipes



Added 7-1-2021 Video with audio from external mics including in between the two tailpipes

 

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Interesting design. Looks nice and if it’s almost 50% off it’s not a bad deal for what you get. I bet the quality is pretty good.
 

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Great price I guess.. But it sounds tame compared to others I heard...17+ with a mid pipe sounds better..jmho
 

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Discussion Starter · #4 ·
The midpipe with the 17+ stock Fujitsubo exhaust definitely sounds better. At least until a pair of catless downpipes are installed then it becomes unbearable between 2-3k RPM at highway speeds.

Trying to find a plan B since the Litchfield system is not available right now and it sounds like this HKS valve stays closed until it is manually opened or RPM reaches 3500+ which may address the drone. Communicating with HKS support now to see how that module is installed since it needs power and tach. Hopefully not vampire taps.
 

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The midpipe with the 17+ stock Fujitsubo exhaust definitely sounds better. At least until a pair of catless downpipes are installed then it becomes unbearable between 2-3k RPM at highway speeds.

Trying to find a plan B since the Litchfield system is not available right now and it sounds like this HKS valve stays closed until it is manually opened or RPM reaches 3500+ which may address the drone. Communicating with HKS support now to see how that module is installed since it needs power and tach. Hopefully not vampire taps.
Did they ever get back to you? i've been considering getting a valved exhaust as well and this looks like a good option
 

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Did they ever get back to you? i've been considering getting a valved exhaust as well and this looks like a good option
Yes, the diagram that HKS Support sent me shows three wires and a manual switch from the control module which are probably switched power, ground, and tach. I asked whether there was an adapter for plug and play and they said no such thing is available.

Can probably tap power and ground directly into fuse box but, unless there's a better method, tach signal will need a tap into ECU harness. Install looks similar to an e-cutout. Not really ideal with soldering tach into stock harness so may just see if manual valve switch can operate independently without the tach signal similar to 2017+.

These HKS 2sx exhausts were a limited run of 20 each for both the GTR and Toyota 86/BRZ. As far as I can tell from the distributor site, there are 3 left in the country for the GTR.
 

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Discussion Starter · #9 ·
Lol yup, with valves closed, it's exactly how it should be... silent. I take it neither of you watched the video until the end where the car was on the Dyno with catless downpipes and valves open?
 

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I loved my HKS and at 76mm had no issue with flowing 1000hp. This one looks absolutely perfect.

I agree should be as quiet as stock with valves closed.

My 3582 setup was as quiet as stock even under part throttle. That’s the only thing I miss about it ;)
 

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Where are you looking at buying this from? Would love to get in on this if the system was actually really loud. Hoping someone has some experience with this exhaust and can provide insight.
 

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Thanks for the share! Same here, waiting to seal the deal on a GTR first though. It's not too far off on price from a Boost Logic setup though, so something to mull over atm. In the end, there could be a limited number of units, but if it sounds like shit, there's no way I'd want to keep it over a better sounding setup lol.
 

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The midpipe with the 17+ stock Fujitsubo exhaust definitely sounds better. At least until a pair of catless downpipes are installed then it becomes unbearable between 2-3k RPM at highway speeds.
Trying to find a plan B since the Litchfield system is not available right now and it sounds like this HKS valve stays closed until it is manually opened or RPM reaches 3500+ which may address the drone. Communicating with HKS support now to see how that module is installed since it needs power and tach. Hopefully not vampire taps.
Hi. Are you saying adding midpipe to a stock 2018 will increase sound but probably cause drone?

Sent from my iPhone using Tapatalk
 

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Discussion Starter · #16 ·
Hi. Are you saying adding midpipe to a stock 2018 will increase sound but probably cause drone? Sent from my iPhone using Tapatalk
It depends on your sensitivity to drone. For those who don't care for it, yes, it will add sound and possibly increase the likelihood of drone with the valves open especially with a non-resonated MP. Can't speak for a 2018 with valves closed since I don't own one. That said, I installed the HKS resonated MP yesterday and I don't recall the AMS one being as drone-y but I could be wrong since that was a 3-4 years ago. Also don't see us taking long road trips anytime soon in this car so probably won't matter.
 

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Contacted HKS. They said it comes with a controller which I had them confirm was a switch. Seems to be hard wired to the system unlike other valvetronic setups such as Armytrix. Attaching what they sent over to this post.

Also, no documentation because fuck me for wanting to know what I'm spending thousands of dollars on. 45th Limited Edition my ass, only thing limited is the support and documentation.
 

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Discussion Starter · #19 ·
Contacted HKS. They said it comes with a controller which I had them confirm was a switch. Seems to be hard wired to the system unlike other valvetronic setups such as Armytrix. Attaching what they sent over to this post.

Also, no documentation because fuck me for wanting to know what I'm spending thousands of dollars on. 45th Limited Edition my ass, only thing limited is the support and documentation.
Lol yeah the responses received from HKS support were not that detailed. They obviously had the digital manual so I'm not sure why they couldn't just screenshot the 3-4 pages with wiring info.

The exhaust just got here today. The valve motor and the pieces are about what I was expecting along with a few extra pieces of supporting hardware that I wasn't expecting (in a good way). In the process of converting the manual to PDF and will upload pictures shortly.
 

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Lol yeah the responses received from HKS support were not that detailed. They obviously had the digital manual so I'm not sure why they couldn't just screenshot the 3-4 pages with wiring info.

The exhaust just got here today. The valve motor and the pieces are about what I was expecting along with a few extra pieces of supporting hardware that I wasn't expecting (in a good way). In the process of converting the manual to PDF and will upload pictures shortly.
Awesome, thanks so much! Please provide information on the exhaust once you've got it installed and had some time with it. Hoping this is very loud and doesn't have drone.
 
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